Abstract: The inventive device is composed of a cylindrical body with a specifically shaped expanding inner bore which is mounted on the barrel of the firearm. This expanding bore constantly increases from the interface with the muzzle of the firearm to the exit plane of the device. Longitudinal slots, parallel to the bore axis, are cut through the body of the device from the outside to the inner bore.

Abstract: The inventive device is composed of a cylindrical body with a specifically shaped expanding inner bore which is mounted on the barrel of the firearm. This expanding bore constantly increases from the interface with the muzzle of the firearm to the exit plane of the device. Longitudinal slots, parallel to the bore axis, are cut through the body of the device from the outside to the inner bore.

Abstract: A gun barrel adapted to be connected to a receiver includes a rifled portion and a smoothbore portion. The rifled portion may have deeper than normal grooves to permit the escape of propellant gases past the bullet. The smoothbore portion includes an increased diameter expansion section, a reduced diameter compression section and an alignment section. Gases expanding past the bullet reduce the peak pressure in the gun barrel and provide a relatively low pressure adjacent the muzzle at the time of bullet exit. The improved gun barrel affords increased bullet velocity and accuracy, and reduced felt recoil.